Technical description and composition of the GOLDSTAR LT-28T350R TV, panel type and modules used. The composition of the modules.GOLDSTAR LED
Model: LT-28T350R
Chassis / Version: JUC7.820.00130484
Panel: C275X15-E6-H
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP4012
MOSFET LED driver: TO-252
Power Supply (PSU): integrated into MainBoard
PWM Power: NCP1251A
MOSFET Power: 70R600P
MainBoard: JUC7.820.00130484
IC MainBoard: CPU: MSMHFK, SPI FLASH: 25Q32CS
Tuner: CH DM121 C816RH
LT-28T350R Specifications
GOLDSTAR LT-28T350R
General recommendations for TV LCD LED repair
Possible manifestations of defects
- TV GOLDSTAR LT-28T350R does not turn on at all. Control lamps do not light up or blink. The TV on the remote control and control panel buttons does not respond.
In this case, the main Switching Power Supply (AC / DC voltage converter), the elements of which are located on the MainBoard JUC7.820.00130484, may be faulty. It is necessary to measure its output voltages, and if they are absent (full or partial), check the serviceability of the power switches (70R600P) of the converters and rectifier diodes for a possible short circuit.
In case of any breakdowns of semiconductors in the secondary circuits, the converter can usually operate normally in an emergency short circuit mode. There are no output voltages. And with a short circuit in the power elements of the primary circuit, as a rule, the mains fuse breaks and, less often, the current sensor in the source of the key.
Breakdown of power switches (MosFet) in switching sources is sometimes caused by malfunctions of other circuit elements, for example, in the circuits supplying the PWM controller, frequency setting or damper, as well as in the circuits of Negative Feedback (OOS) stabilization. PWM controllers (PWM) NCP1251A, if they have no visible damage to the case and an outright short circuit between the terminals, are usually checked by replacing.
- There is no picture, but there is sound and reaction to the remote control. Or the image may appear for a second immediately after switching on.
A malfunction is usually in these cases most likely in the backlight units of the display matrix. The reason may be in the breakage of the LEDs, in the stabilization of their power supply, or in the violation of the contact connections of the strings connectors,
To test the LED strips, in order to open all the transitions of the LEDs, several tens of volts or more are needed; it is best to use a current source for such purposes. The breakage of several PN junctions connected in series cannot be detected with a multimeter or tester. In such cases, it is necessary to open the panel and check each LED. If your multimeter cannot open the LED junctions in forward bias, you can sometimes detect the presence of a protective zener diode PN junction by connecting the probes in the opposite direction. If the zener diode is cut off or broken in the K / Z, then the LED is faulty and requires replacement.
- The TV does not turn on, the indicator signals the standby or operating mode, or blinks.
Repair or diagnostics of the JUC7.820.00130484 motherboard should begin with checking the stabilizers and power converters necessary to power the microcircuits and matrix. If necessary, you should update or replace the software (software). In some cases, to repair the MB (SSB) board, it may be necessary to replace the chips - CPU: MSMHFK, SPI FLASH: GD25Q32 with new or known good ones. In cases where BGA technologies are used, defects are usually localized by heating.
Before changing the CH DM121 C816RH tuner, if it is not possible to tune to television channels, you should make sure that there are supply voltages, which must be measured at the corresponding tuner terminals and check the software for correctness. The pulses of data exchange between the tuner and the processor can be monitored with an oscilloscope
Attention to TV owners! Attempts to repair the GOLDSTAR LT-28T350R on your own are not recommended by the manufacturer and can lead to serious negative consequences!
DOWNLOAD FIRMWARE FOR SPI FLASH -----------> GOLDSTAR LT-28T350R, Main: JUC7.820.00130484, Panel: C275X15-E6-H
The appearance of the MainBoard JUC7.820.00130484 is shown in the figure below:JUC7.820.00130484
Main features of the GOLDSTAR LT-28T350R device:
Installed matrix (LED panel) C275X15-E6-H.
To power the backlight LEDs, a converter combined with the JUC7.820.00130484 main board is used, controlled by the MP4012 PWM controller. TO-252 switches are used as power elements of the LED driver.
The power module is combined with the MainBoard and is made according to the AC / DC flyback voltage converter circuit using NCP1251A microcircuits and power switches of the 70R600P type.
MainBoard - the main board (motherboard) is a JUC7.820.00130484 module, using CPU chips: MSMHFK, SPI FLASH: 25Q32CS and others.
Tuner CH DM121 C816RH provides reception of television programs and tuning to channels.
GOLDSTAR LT-28T350R TV with LCD C275X15-E6-H, 28 "(71 cm) diagonal 16: 9. The required brightness of the 280 cd / m² screen is provided by LED backlight. Dynamic contrast ratio of 100,000: 1 is achieved by special control operation of LEDs. The technology of production of the screen of this TV model is realized LED LED backlight. It is possible to view images in high quality HD at a resolution of 1366x768 pixels in the standard of graphic decomposition 720p (HD Ready). Supported multimedia file formats: MP3, MKV, JPEG.
Speaker power 12 W (2x6 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
External interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x2, component, VGA, HDMI x3, MHL, USB. A headphone output is provided.
The digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Overall dimensions: 730x505x135 mm.
Attention! Panel C275X15-E6-H of LED TV GOLDSTAR LT-28T350R is an expensive and unreliable element.
Do not allow any impact on the glass and pressure on the screen surface to avoid damage to the LED panel!
It is also unsafe for liquid to spill onto the screen. Sometimes one drop is enough if it drips down the glass onto the cables to make the TV unrepairable.